I have tried Mathematica 8.0.4 for Windows on a laptop
running Vista Ultimate 64-bit with a T9400 (at 80% speed).
There was a previous version (7.x.x) that I have uninstalled
(so I cannot do more tests...).
Anyway, before uninstalling, since I was curious about the
relative performance of the two versions, I have saved a notebook
with a few line of code (each repeated at least 3 times).
Here are two examples:
Timing[Select[Range[5 10^5], EulerPhi[#] + # == DivisorSigma[1, #] &]]
(* v7 about 12 seconds, v8 13.4 seconds, i.e. about 10% slower *)
Timing[Select[Range[12], Reduce[x^2 - # y^2 == 1 + x y && x > 0 && y > 0,
{x, y}, Integers] === False &]]
(* v7 about 10.1 seconds, v8 14 seconds, about 35% slower *)
In another case v8 was much faster:
Timing[Sum[N[1/x] Log[x], {x, 2, 10^6}]]
(* v7 about 7.6 seconds, v8 about 0.2 seconds i.e.
about 35 times faster *)
To be honest, my interest in Windows version is marginal (the laptop
is just for emergencies) since our official Mathematica
licence is for linux, but I'm still wondering if upgrading to v8
can be useful even if one is not interested in all the new
features.
thanks